Dogs' cancer rates high in area known as "triangle of death."

Apr 20, 2009

Marconato, L, C Leo, R Girelli, S Salvi, F Abramo, G Bettini, S Comazzi, P Nardi, F Albanese and E Zini. 2009. Association between waste management and cancer in companion animals. Journal of Veterinary Internal Medicine doi:10.1111/j.1939-1676.2009.0278.x .

Synopsis by Paul Eubig, DVM

Dogs are more likely to develop cancer if they live near Naples, Italy, where illegal waste disposal commonly occurs and people have a high rate of cancer deaths.

Dumping and burning of garbage in cities near Naples, Italy -- but not in Naples itself -- is associated with a higher risk of cancer in dogs living in those urban settings.

Other studies from the Naples region document high rates of people dying from cancer, especially in an area northeast of Naples called the “triangle of death." This study corroborates these findings from humans and  suggests that the health of animals can serve as a sentinel to warn of human health problems.

The cause of the cancers was not identified. A separate study cited finds higher levels of the carcinogen dioxin in milk from local farms, but the researchers did not measure dioxin or other chemicals in the dogs.

The region's severe waste problem occurs because industrial waste and household garbage are dumped on streets or burned, polluting air, water and soil.

Studying pets is a good way to understand and examine human health. Identifying specific risks in people is difficult because people live long lives, tend to move, and are exposed to a variety of chemicals during their lives.

However, pets have shorter lifespans, often live in the same place and do not smoke or drink alcohol and coffee. These differences allow researchers to zero in on the aspects of their lives that can be risky, such as living in a polluted city.

The veterinarians who led the study compared cancer rates in dogs living in Naples to rates in the surrounding cities where improper waste disposal is worse. They collected information about the dogs, such as where the dogs lived, what type of food they ate and whether they lived with a cigarette smoker.

The dogs that lived in several cities around Naples were more than twice as likely to develop lymphatic cancer as dogs that lived in Naples. They also found that dogs living with smokers were more likely to develop cancer. The cancer risk from the second hand smoke was separate from the cancer risk from living outside of Naples, but added to the risk of cancer in the dogs in this study.